More than 20 years ago, Professor Steven Levitt argued that gamblers systematically undervalue National Football League (NFL) underdogs.
Underdogs had a >50% ATS record in 26 of the past 34 regular seasons through 2025-26.
I will keep track of the all-underdogs ATS record for the NFL 2026-2027 season
15% of matches were reversed on points against the spread (ATS) in each of the past 3 seasons -- below the long-term trend established over the previous 3 decades.
So, it is possible that the prior misperception may no longer be there in the betting market that overdog favorites will win by larger margins than turn out to be the case.
Underdogs only won 2025-26 ATS by winning a higher-than-expected % of matches outright.
Based on what seemed like regularities in place up until 2022-23, I expect underdogs to win a bit more than 1/3 of all matches straight-up and a bit more than 1/6 of all matches on points.
Are the unusual results of the past 3 seasons just short-term random walks around long-term averages? Or has the underdog-tilt identified by Professor Steven Levitt vanished? We will need a few more seasons to reach a conclusion.
I stuck with regular-season underdogs in 2025-26 in the just-for-fun pool that Godiva boy toy Archibald introduced me to. Because most pool players back overdog favorites, I finished 1st out of 54 players in Archibald's pool.
I should say that the all-underdog long-term winning % ATS was not high enough to make a living against the small commissions implicitly built into odds offered by gambling houses.
Sports betting is the House of the Rising Sun of the 3rd millenium: "the ruin of many a poor boy". Dare I say that the 19th century House of the Rising Sun was more fun for customers, but not workers, and that 21st century gambling is not much fun over the long run for almost all customers.
